Open your geometry box. There are some drawing tools. Observe them and complete the following table:
| Name of the tool | Number of lines of symmetry |
|---|---|
| (i) The Ruler | _____ |
| (ii) The Divider | _____ |
| (iii) The Compasses | _____ |
| (iv) The Protractor | _____ |
| (v) Triangular piece with two equal sides | _____ |
| (vi) Triangular piece with unequal sides | _____ |
| Name of the tool | Number of lines of symmetry |
|---|---|
| (i) The Ruler | 2 |
| (ii) The Divider | 1 |
| (iii) The Compasses | 0 |
| (iv) The Protractor | 1 |
| (v) Triangular piece with two equal sides | 1 |
| (vi) Triangular piece with unequal sides | 0 |
What is a line of symmetry?
( ext{A line of symmetry divides a shape into two mirror halves.})
( ext{After folding on that line, both halves match exactly.})
(i) The Ruler (think of it as a rectangle)
( ext{A rectangle has a vertical symmetry line through its center.})
( ext{It also has a horizontal symmetry line through its center.})
Therefore: 2 lines of symmetry (ignore the printed markings).
(ii) The Divider (two equal arms joined at a hinge)
( ext{When both arms are opened equally, there is one middle line.})
( ext{This middle line is the angle bisector and acts as symmetry.})
Therefore: 1 line of symmetry.
(iii) The Compasses (one arm has a pencil, the other a needle)
( ext{The two arms are not identical.})
( ext{No fold can make both sides match perfectly.})
Therefore: 0 lines of symmetry.
(iv) The Protractor (a standard 180° semicircle with a straight base)
( ext{There is one line through the center, perpendicular to the base.})
( ext{This line splits the semicircle into two equal mirror parts.})
Therefore: 1 line of symmetry.
(v) Triangular piece with two equal sides (an isosceles triangle)
( ext{The line from the top vertex to the midpoint of the base})
( ext{splits the triangle into two equal halves.})
Therefore: 1 line of symmetry.
(vi) Triangular piece with unequal sides (a scalene triangle)
( ext{All sides and angles are different.})
( ext{No fold can make both halves match.})
Therefore: 0 lines of symmetry.
Quick check: ruler = 2, divider = 1, compasses = 0, protractor = 1, isosceles set-square = 1, scalene triangle = 0.